Fluid pressure system



Nov. 15; 1949 J. KELLOGG I 2,488,086

FLUID PRESSURE SYSTEM Filed Aug. 27, 1945 v 5 Sheets-Sheet l Nov 15, 1949 J. KELLOGG 2,488,086

FLUID PRESSURE SYSTEM 3 Sheets-Sheet 2 Filed Aug. 27, 1945 Patented 15, 11-949 UNITED STATES PATENT OFFICE zaaaoac Q FLUID" PRESSURE SYSTEM Joseph Kellogg, Milwaukee, Wia, assignor to Nordberg Manufacturing Company, Milwaukee, Wis a corporation of ApplicationAugust 27, 1945, serial No. 612.932

This invention relates to'fluid pressure systems and more particularly to a fluidpressure system for use in. connectionv with hydraulic brakes or the like.

In mine. hoistsor' the like, the drum on: which the hoist cable is wound is necessarily large and heavy. Such drums are usually controlled by brakes which are held set constantly by a plurality of weights and released by a hydraulic cylinder which counteracts the weights to release the brake when it is desired to operate the hoist. In order to insure proper operation of the drum, it is necessary to have a large reserve tank of oil under constant high pressure.

In some oil reserve tanks the level of oil in the tank is maintained by an oil pump, which pumps. against air pressure in the tank. The air in the tank is supplemented continuously with air introduced. into the intake of the pump through a sniiter valve. This system has the disadvantage that the air so snifted has a tendency to remainin suspension and therefore may be carried away in greater volume than supplied. The air in suspension results in erratic or spongy operation when used to actuate the brake.

One object of the present invention is to provide a pressure system for hydraulic brakes which will automatically maintain the proper supply of oil and air in the pressure reserve tank.

Another object is to provide a pressure system for hydraulic brakes, or the like, in which the oil will contain a minimum of air in suspension.

A further object is to provide a pressure system for hydraulic brakes, or the like, which will insure uniform brake action.

A still further object is to provide a pressure system for hydraulic brakes, or the like, in which air is automatically separated from the oil or other brake fluid.

A further object is to prevent spongy operation of the brakes.

Another object is to provide a pressure system for hydraulic brakes, or the like, in which air is automatically replenished as it is depleted.

Other objects will become apparent upon considering the following specification, which, when taken in connection with the accompanying drawings illustrate a preferred type of the invention.

In terms of broad inclusion the invention comprises a pressure tankadapted to retain brake fluid or the like underpressure,-a pump adapted to supply brake fluid to said tank, means to introduce air into the brake fluid on the suction side of the" pump, and means on the pressure side reclaim. (Cl. it s-1i of the pump to separate the air from the brake fluid.

In the drawings:

Fig. 1 is an elevational view, partly in crosssection, ofa pressure tank for a hydraulic brake system embodying the present invention;

Fig. 2 is a cross-section taken on; the line 2-2 of Fig. 1', lookingin the direction of the arrows;

Fig. 3 is a cross-section taken on theline 3-4 of Fig. 2, looking in the direction of the arrows;

Fig. 4 is arr-enlarged cross-sectional, elevational view through the control valve shown in Fig. 1-; and

Fig. 5 is a cross-sectional elevational view of the control valve taken on a plane at right angles to that of Fig. 4.

Referring to the drawings, the pressure system for the hydraulic apparatus comprises a pressure tank Ill, mounted by means of a plurality of posts l2 or'i top of a sump tank I4 with a pumping system comprising a pair of positive displace-- ment pumps l6 and I1 drawing the oil or other fluid from the sump tank H and delivering it under pressure to the lower part of a circular standpipe I8 which is closed at the bottom and projects through the lower side of the pressure tank It. The pumps I 6 and II are actuated by motors 20 and 2|, mounted adjacent the pumps l6 and I1 and on the top of the sump tank M.

The motors 20 and 2| are controlled by pressure control switches 25 and 26, respectively, which start the motors 20 and 2| when the pressure within the tank I 0 falls below a predetermined minimum and shut the motors oil when the pressure within the-tank reaches a desired maximum.

The switches 25 and 26 are so arranged that pressure switch 25 will cut the motor 20 in as the pressure drops to within a few pounds of the desired minimum, and the pressureswitch 26 will cut in the motor 2| when the pressure of air reaches the desired minimum. Both switches 25 and operate to cut of! the motors 20 and II when the air pressure builds up to the desired maximum.

The pump [6 is adapted to draw oil or brake fluid from the sump tank ll through a suction pipe 30, past a screen 3|, through the pump it and discharge the oil from the pump at increased pressure through a pipe 33. I

Similarly the pump I1 is adapted to draw oil or brake fluid from the sump tank It through a suction pipe 35, past a screen 36, through the pump "and discharge it at increased pressure through a pipe 31.

2,4ee,oae

The discharge pipes 55 and 81 Join in a'Y 48 which discharges into a pipe 42. The pipe 42 enters the lower end 01' the standpipe l8 atone side thereof, so that the oil discharged from the pump enters the standpipe l8 tangentially and causes the oil to assume a whirling motion, the whirling motion creating a vortex as shown at 44. Thecentriiugal force created by, the whirling fluid causes air entrained and suspended in the fluid to be forced toward the center and escape through the surface of the vortex 44.

The level of the oil in the reservoir 18 and the amount of air above the surface of the gill are both governed by a float controlvalve, generally designated 58, and best seen in Figs. 4 and 5.

Referring to the details of the .control .valve 58, as seen in Figs. 4 and 5, the valve comprises v a body portion 52, having a vertical aperture 58 therethrough, which accommodates a multiple plunger valve 54. The multiple plunger valve 54 comprises three separate plungers 55. 58 and51 fixed on a common stem. Movement of the plunger valve 54 is eflected by a float 88. The float 88 is pivoted on a standard or post 8| and actuates the valve 54 through a connecting rod 88.

When the tank I8 is empty the float 88 and the valve 54 are in their lowermost position, as seen in Fig. 5. At that time, any air under pressure in the tank I8 is exhausted through a vent pipe 84 which opens into the tank l0 above the minimum desirable oil level therein and leads into a port 85 in the aperture 53 just above the lowermost position of the plunger 51. Air passing out through the vent pipe 84 passes upwardly past the lower edge of the plunger 58, and out through an opening 81 in the valve body 52. The opening 81 has a pipe 88 connected thereto which opens into the sump tank 14, so that the top of the plunger 51 is below the port 65, air under pressure in the tank l8 vents from the tank i8 through the pipe 84, past the plungers 51 and 58, through the opening 81 and the pipe 88 and into the top of the sump tank l4 which is open to the atmosphere.

As the oil level in the tank I8 builds up, the float rises, lifting the plunger valve 54 coverin the port 65 with the plunger 51 to prevent further escape of air from the tank I8. As the level of the oil in the tank I0 rises above a desired minimum the plunger 55 uncovers a pair of ports 12-18, permitting air to flow at atmospheric pressure from the sump tank 14, through a pipe 15, into the port 12, past the plunger 55, into the port 13, and out through a pipe 11, and into the intake pipes 38 and 35 of the pumps i8 and i1 permitting the pumps i6 and I1 to pump a mixture of oil and air. Thus the pumps serve, not only to replenish the oil in the tank ill, but also to replenish the air.

When the oil level reaches a desired maximum. the plunger 56 uncovers a port 88 which opens into the tank i8 and permits oil to drain from the tank ill, through the port 68, past the plunger 58. through the opening 81 and pipe 68 into the sump tank i4. The oil continues to drain through the port 88 until the level of the oil in the tank again drops below the desired maximum.

.The pumps [8 and i1 continue to operate until the air pressure in the tank builds up to the maximum desired, at which time the pressure switches 25 and 26 operate to shut 01! power to the motors 28 and 2|, stopping the pumps.

The three controls, namely the pressure control valves 25 and 28, the plunger-valve 55 controlling the admission of air into'the intakes 30 and 55 o! the pumps l8 and i1, and the valve 58 controlling the discharge of surplus oil from the tank ll, all cooperate to maintain a suiflcient supply 01' oil in the tank, together with a suflicient air cushion to minimize pressure fluctuation as the oil level in the tank changes.

A drain pipe 81 is connected to a port in the bottom of the valve 58 to drain all oil from the tank It at such time as it may be desirable to do so. The pipe 81 has a hand operated valve 88 to control the draining operation.

. The top of the tank l8 may be supplied with a compressed air connection 88 through which compressed air may be supplied, if available, to decrease the time necessary to build up pressure through tlie'pumps i8 or i1.- I

A safety valve 8i is provided in the bottom of the tank i8. Thevalve 8| is set to empty the tank iilwhen the pressure within the tank is excessive. Y I I Ope ation In operation, the system may be started with oil in the sump tank [4 and neither oil nor pressure in the pressure tank it, or there may be oil and pressure in the pressure tank. v when the current is switched on with no-oil or. pressure in the tank ill, the switches 25 and 28 start both motors 28 and-2| which actuate pumps l8 and I1, respectively, to pump oil iromthe sump tank l4, through the pipes 38 and 35 and the screens 3| and 88, into the. pumps l8 and I1 and out of the pumps through the pipes38zand 81, past the Y 48, through the pipe 42 and into the standpipe l8 tangentially to its periphery. As the oil enters the standpipe i8 tangentially under pressure it assumes 'a whirling motion which, as it rises in the standpipe, creates the vortex 44. The centrifugal force of the whirling oil forces the heavy oil outward and forces the lighter air in the oil toward the center of the vortex, and out into the free air in the top of tank [0. The vortex further creates a large area through which the air may escape more readily. The oil, thus freed of air spills over the upper lip of the standpipe l8 into the bottom of the. tank I.

Until the oil has risen to a'predetermined level the air in the top of the tank passes out through the pipe 84, through the ports 85 and 81 and through the pipe 88 to the top of the sump tank l4, which is open to the atmosphere.

As the level of the liquid rises, the float 88 moves upwardly raising the multiple plung'er valve 54, and closing communication between the pipes 84 and 88.

Further raising of the level of the liquid causes the plunger 55 to open communication between the ports '12 and 13 which permits air to pass from the atmosphere in the top of the sump tank l4, through the pipe 15, through the ports 12 and I3 in the valve body, and through the pipe 11 into the intake pipes and 35 of the pumps is and I1. Thus as the pumps continue to pump oil they simultaneously draw air from the atmosphere into the intakes of the pumps and pump it with the oil into the tank 15' to s. raise the air pressure withinthe tank. The air so introduced into the oil during pumping is' separated from the oil by centrifugal force resulting from theoil whirling in the standpipe II, as explained above.

As the air pressure in the tank It is built up by the introduction of air the oil level continues to rise in the, tank due to-the simultaneously pumping of oil and air until the plunger 56 uncovers the port 80. At that point oil bleeds out through the ports 80 and Hand through the pipe 68 into the sump tank ll. During the time the oil is draining, air continues to flow through the valve 50 and into the intake of the pumps I 8 and I1 to build up the air pressl'lre within the oil pressure tank I it.

When the pressure has risen'to a predetermined maximum, the pressure, actuated switches 25 and 26 cut out the motors 20 and 2| to stop the pumping of both oil and air. After pumping has ceased, oil will continue to drain back into the sump tank-i4, through thep'ortstii, 61 and the pipe 68, until the level of liquid falls to a point where the float 60 moves the-plunger 56 downward to shut off the port -80.

When it is desired to release the brake, oil is delivered to the brake cylinder from the oil pressure tank through a supply pipe 92. When a predetermined amount of oil has been withdrawn through the pipeSZ, the air pressure will drop suiliciently to permit the switch 25 to cut in the motor 20 operating the pump l6. Should oil continue to be withdrawn at a greater rate than it is replenished, the pressure in the tank will continue to fall, and the switch 26 will then cut in the motor'2l starting the second pump II.

If compressed air is available, the time required to build up the necessary pressure in the tank i may be decreased considerably by charging the tank with compressed air through the pipe 90 when the tank is partly filled with oil.

In the event the pressure should at any time become great enough to affect the safety of operation, a safety valve 9| will open, permitting oil to flow out of the tank in into the oil sump tank II.

-It is to be understood that the form of the invention herein shown and described is to be taken merely as a preferred example thereof, and that various changes in size, shape and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

That which is claimed as new and is desired to be secured by Letters Patent is:

1. In a device of the character described, an oil pressure tank, a pump adapted to deliver 011 to said tank, means within said tank to introduce air into the oil pump on the suction side thereof when the air in the top of the tank becomes depleted, said last named means continuing to function until the air pressure reaches a desired maximum and the liquid level reaches a desired minimum.

2. In an oil pressure reserve tank for hydraulic brakes or the like, a pump adapted to deliver oil and air to said tank, and means in said tank to drain oil from said tank when the liquid level in the tank is above a desired maximum.

3. In an oil pressure tank for hydraulic brakes or the like, a pump adapted to deliver a mixture of oil and air to said tank, means in said tank to govern the flow of -air into the oil being pumped, means to drain oil from the tank after the oil has exceeded a predetermined maximum tank, and means to stop level, and means to stop the pump when the air pressure in the tank reaches a predetermined maximum.

4. In an oil pressure reserve tank for hydraulic brakes or the like, a pump adapted to deliver oil and air to said tank, means in said tank to drain oil from said tank when the level 0! oil in the tank is above a predetermined maximum, and means to separate air from the oil within said 5. In an oil pressure tank for hydraulic brakes or the like,

a pump adapted to deliver a mixture of oil and air to said tank, means in said tank to govern the flow of air into the all being pumped, means to drain oil from the tank when the 'oil level exceeds a predetermined maximum, means to separate airirom the 011 within said pressure in said tank reaches a desired maximum. 6. In a device of the character described, an oil pressure tank. a. standpipe mounted in the bottom -01 :said tank projecting therebelow, and communicating with the tank at the upper'end oi the standpipe, a pump adapted to deliver oil into said standpipe, means to actuate said pump, Pressure responsive means adapted to start the motor when pressure within the tank drops below a desired minimum, and to stop the motor when pressure within the tank reaches a desired maximum, means within said tank to bleed air into the oil being pumped when the level of oil within the tank reaches a desired minimum and means to bleed oil out of said tank when the level therein exceeds a desired maximum.

'L-A device as defined in claim 6 including means to effect separation of the air in suspension from the oil entering the tank.

8. A device as recited in claim 6 including means to create a centrifugal force within said sililandpipe to separate air in suspension from the o 9. In a device of the character described an oil pressure tank, a standpipe mounted in the bottom of said tank projecting therebelow, and communicating with the tank at the upper end of the standpipe, a pump adapted to deliver oil into said standpipe tangentially thereto, means to actuate said pump, pressure responsive means adapted to start the motor when pressure within the tank drops below a desired minimum, and to stop the motor when pressure within the tank reaches a desired maximum, means to bleedair into the oil being pumped when the level of oil within the tank is above a desired minimum, and means to bleed oil out of said tank when the level therein exceeds a desired maximum.

10. In a device of the character described, a sump tank, a pressure tank mounted on said sump tank, a standpipe having a closed lower end projecting through the lower part of said pressure tank, opening into said pressure tank and terminating above said sump tank, a pump mounted on said sump tank, a motor adapted to actuate said pump, a pressure responsive switch adapted to cut in the motor when pressure in the tank drops below a predetermined minimum and cut out the motor when the pressure reaches a predetermined maximum, an intake pipe for said pump extending into said sump tank, an exhaust pipe for said pump delivering fluid to said standpipe adjacent the bottom thereof and tangentially thereto, and a valve within said pressure tank adapted to deliver air to said intake pipe when the liquid level in the pressure tank exceeds a-desired minimum and to drain oil from said pump when the air mam said pressure tank when the liquid level exceeds a desired maximum. I

11. In an oil pressure reserve tank for hydraulic brakes or the like, a pump adapted to deliver oil and air to said tank, and a float controlled valve adapted to drain oil from said tank when the liquid level in the tank is above a desired maximum.

12.1n an oil pressure reserve tank for bydraulic brakes or the like, a pump adapted to deliver 011 and air to the tank, a float controlled valve adapted to drain oil from said tank when the level of the oil in the tank is above a predetermined maximum, and means opening into said tank to separate the air irom the oil.

13. In an oil pressure reserve tank for hydraulic brakes or the like, a pump adapted to supply a mixture of air and oil 'to said tank, a float controlled valve adapted to govern the flow of air into the oil being pumped and to drain oil from said tank when the level of oil 'therein is above a predetermined maximum, and means opening into said tank to separate the air from the oil,

14. An oil pressure reserve tank for hydraulic brakes or the like, as defined in claim 13, including a pressure actuated switch operable upon the attainment of a desired maximum air pressure within said tank to stop said pump.

15. In an oil pressure reserve tank a pump adapted to deliver a mixture of air and oil to the tank, and a valve adapted to vent air when the level of oil is below a desired minimum and to deliver air to said pump when the level of oil is above a desired minimum.

16. In a pressure system for hydraulic brakes or the like, a tank, a pump adapted to deliver a mixture of liquid and air to said tank under pressure, and a float controlled valve to direct air into the liquid being pumped when the level of oil in the tank is above a desired minimum, to drain oil from the tank when the level of oil is above a desired maximum, and to vent air from the tank when the level of oil is below a desired minimum.

17. In a device of the character described, an

oil pressure tank, a pump adapted to deliver oil to said tank, and-means lb introduce air into the oil entering the pump to replenish the air in the tank until both the air pressure and the liquid level reach predetermined amounts.

18. In an oil pressure reserve tank for hydraulic brakes. or the like, a pump adapted to deliver oil and air to the'tank, a float controlled valve adapted to drain oil from said tank when the level of the oil in the tank is above a predetermined maximum, and means opening into said tank above the upper maximum level of oil therein to separate the air from the oil.

19. In an oil pressure reserve tank for hydraulic brakes or the like, a pump adapted to supply a mixture of air and oil to said tank, a float controlled valve adapted to govern the flow of air into the oil being pumped and to drain oil from said tank when the level of oil therein is above a predetermined maximum, and means opening into said tank above the upper maximum level of oil therein to separate the air from the oil.

JOSEPH KELLOGG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'ENTS Number Name Date 1,372,928 Barton Mar. 29, 1921 1,475,683 Carrey Nov. 27, 1923 1,549,786 Mohr Aug. 13, 1925 1,567,148 Jennings Dec; 29, 1925 1,623,103 Frederick Apr. 5, 1927 1,749,797 Anderson et al. Mar. 11, 1930 2,228,401 Pressler Jan. 14, 1941 2,327,601 Kent Aug. 24, 1943 2,347,472 Dorward Aug. 25, 1944 FOREIGN PATENTS Number Country Date 418,836 Great Britain 1934 785,896 France 1935 

